This experiment was conducted to evaluate the effect of exogenous enzyme (3 g kg- DM), formaldehyde (30 and 60 g kg- DM) and or sodium hydroxide (40 g kg- DM) on in vitro gas production parameters of sunflower meals (25 and 165 g fat kg- DM) were with gas production techmque and using fistulated sheep rumen fluid. Kinetics of gas production was fitted to an exponential model. Sodum hydroxide and enzyme treatments significantly increased gas production (B), Metabolizable Energy (ME), Organic Matter Digestibility (OMD), Net Energy Lactation @EL), ammonia-N (NH,-N) and Shod Chain Fatty Acid (SCFA) but formaldehyde decreased them. The lowest of gas production was estimated for low fat sunflower meal treated with 60 g formaldehydekg DM (75.9 mLl500 mg DM). There was significant dfference among samples for gas production rate Comtant (C). Sodum hydroxide treated high fat sunflower meal had the hghest of ME, OMD, NEL and SCFA (35.8 MJ kg- DM, 207.5 g kg- OM, 2.42 Mcal kg- DM and 1.53 pmol L-I, respectively). Ammonia-N concentration of hgh fat sunflower meal were the hghest (40.9 mgIl00 mL) The values of B, ME, OMD, NEL, NH,-N and SCFA for low fat sunflower meal was less than hgh fat sunflower meal. The results showed it may be that gas production parameters of low fat and hgh fat sunflower meal are influenced by exogenous enzyme, formaldehyde andNaOH.

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